HDU ACM 1 1016 Prime Ring Problem

彻底掌握前每天撸一遍

#include <cstdio>
#include <algorithm>
using namespace std;
int Lu[21], Hui[21];
int Yi[12] = {2,3,5,7,11,13,17,19,23,29,31,37};
int N, num = 1;
bool Zheng(int a)
{
	for (int i = 0; i < 12; i++)
		if (a == Yi[i])
			return true;
	return false;
}
void dfs(int a)
{
	if (a == N && Zheng(Lu[a - 1] + Lu[0])){
		for (int i = 0; i < a - 1; i++)
			printf("%d ", Lu[i]);
		printf("%d\n", Lu[a - 1]);
	}
	for (int i = 2; i <= N; i++){
		if (Hui[i]){
			if (Zheng(i + Lu[a - 1])){
				Hui[i] = 0;
				Lu[a++] = i;
				dfs(a);
				Hui[i] = 1;
				a--;
			}
		}
	}
}
int main()
{
	int num = 1;
	while (scanf("%d", &N) != EOF)
	{
		printf("Case %d:\n", num++);
		memset(Hui, 1, sizeof(Hui));
		Lu[0] = 1;
		dfs(1);
		printf("\n");
	}
	return 0;
}